Add Windows support to build system and improve dep detection

Use platform-specific library names for skip detection (.so vs .lib).
Find qt-cmake on Windows (qt-cmake.bat). Set CMAKE_BUILD_TYPE on dep
builds. Use explicit Qt6*_DIR variables instead of fragile
QT_ADDITIONAL_PACKAGES_PREFIX_PATH for finding locally-built QtOpcUa.

On Windows: copy DLLs to bin/ (no RPATH), point to system OpenSSL.
On Linux: keep existing symlink approach for open62541 libs.

2 files changed, 50 insertions, 15 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6a9265f..f35b498 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -8,9 +8,14 @@ set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 # Build external dependencies (open62541, qtopcua) if not already built
 include(cmake/BuildDeps.cmake)
 
-# Tell Qt's find_package to also look in our local QtOpcUa install for
-# components (Qt6Config.cmake only searches its own install dir by default).
-list(PREPEND QT_ADDITIONAL_PACKAGES_PREFIX_PATH "${QTOPCUA_INSTALL_DIR}")
+# Point CMake directly at the locally-built QtOpcUa packages.
+# Qt6Config.cmake uses NO_DEFAULT_PATH when searching for components, so
+# QT_ADDITIONAL_PACKAGES_PREFIX_PATH should work but is fragile in practice
+# (Qt Creator can interfere). Setting <Package>_DIR is always checked first.
+set(Qt6OpcUa_DIR "${QTOPCUA_INSTALL_DIR}/lib/cmake/Qt6OpcUa")
+set(Qt6OpcUaPrivate_DIR "${QTOPCUA_INSTALL_DIR}/lib/cmake/Qt6OpcUaPrivate")
+set(Qt6OpcUaTools_DIR "${QTOPCUA_INSTALL_DIR}/lib/cmake/Qt6OpcUaTools")
+set(Qt6DeclarativeOpcua_DIR "${QTOPCUA_INSTALL_DIR}/lib/cmake/Qt6DeclarativeOpcua")
 list(PREPEND CMAKE_PREFIX_PATH "${OPEN62541_INSTALL_DIR}")
 
 find_package(Qt6 6.10.2 REQUIRED COMPONENTS Core Qml Quick OpcUa)
diff --git a/cmake/BuildDeps.cmake b/cmake/BuildDeps.cmake
index 890da57..b402510 100644
--- a/cmake/BuildDeps.cmake
+++ b/cmake/BuildDeps.cmake
@@ -32,7 +32,14 @@ endif()
 # ======================================
 # open62541
 # ======================================
-if(NOT EXISTS "${OPEN62541_INSTALL_DIR}/lib/libopen62541.so")
+
+if(WIN32)
+  set(open62541_lib "open62541.lib")
+else()
+  set(open62541_lib "libopen62541.so")
+endif()
+
+if(NOT EXISTS "${OPEN62541_INSTALL_DIR}/lib/${open62541_lib}")
 
   message(STATUS "Configuring open62541 in ${OPEN62541_BUILD_DIR}...")
   set(_cmd
@@ -43,6 +50,7 @@ if(NOT EXISTS "${OPEN62541_INSTALL_DIR}/lib/libopen62541.so")
       "${OPEN62541_BUILD_DIR}"
       -G
       Ninja
+      -DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}
       -DCMAKE_INSTALL_PREFIX=${OPEN62541_INSTALL_DIR}
       -DBUILD_SHARED_LIBS=ON
       -DUA_ENABLE_ENCRYPTION=OPENSSL
@@ -77,9 +85,15 @@ endif()
 # QtOpcUa
 # ======================================
 
-find_program(QT_CMAKE_COMMAND bin/qt-cmake REQUIRED)
+find_program(QT_CMAKE_COMMAND NAMES qt-cmake qt-cmake.bat PATHS ${CMAKE_PREFIX_PATH} PATH_SUFFIXES bin REQUIRED)
 
-if(NOT EXISTS "${QTOPCUA_INSTALL_DIR}/lib/libQt6OpcUa.so")
+if(WIN32)
+  set(qtopcua_lib "Qt6OpcUa.lib")
+else()
+  set(qtopcua_lib "libQt6OpcUa.so")
+endif()
+
+if(NOT EXISTS "${QTOPCUA_INSTALL_DIR}/lib/${qtopcua_lib}")
 
   message(STATUS "Configuring qtopcua in ${QTOPCUA_BUILD_DIR}...")
   set(_cmd
@@ -90,10 +104,15 @@ if(NOT EXISTS "${QTOPCUA_INSTALL_DIR}/lib/libQt6OpcUa.so")
       "${QTOPCUA_BUILD_DIR}"
       -G
       Ninja
+      -DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}
       -DCMAKE_INSTALL_PREFIX=${QTOPCUA_INSTALL_DIR}
       # Use our locally-built open62541, not the bundled copy
       -DINPUT_open62541=system
       -DCMAKE_PREFIX_PATH=${OPEN62541_INSTALL_DIR})
+  if(WIN32)
+    # Install with: winget install ShiningLight.OpenSSL.Dev
+    list(APPEND _cmd -DOPENSSL_ROOT_DIR:PATH="C:/Program Files/OpenSSL-Win64")
+  endif()
   execute_process(COMMAND ${_cmd} RESULT_VARIABLE _result)
   if(_result)
     list(JOIN _cmd " " _cmd_str)
@@ -120,12 +139,23 @@ else()
   message(STATUS "qtopcua already built, skipping")
 endif()
 
-# The QtOpcUa backend plugin uses $ORIGIN-relative RUNPATH that resolves to
-# qtopcua-install/lib/. Symlink the open62541 libs there so dlopen finds them.
-file(GLOB _open62541_libs "${OPEN62541_INSTALL_DIR}/lib/libopen62541*")
-foreach(_lib ${_open62541_libs})
-  get_filename_component(_name ${_lib} NAME)
-  if(NOT EXISTS "${QTOPCUA_INSTALL_DIR}/lib/${_name}")
-    file(CREATE_LINK ${_lib} "${QTOPCUA_INSTALL_DIR}/lib/${_name}" SYMBOLIC)
-  endif()
-endforeach()
+if (WIN32)
+  # On Windows DLLs must be next to the .exe (no RPATH). Copy them to bin/.
+  file(MAKE_DIRECTORY "${CMAKE_BINARY_DIR}/bin")
+  file(GLOB _dep_dlls
+    "${OPEN62541_INSTALL_DIR}/bin/*.dll"
+    "${QTOPCUA_INSTALL_DIR}/bin/*.dll")
+  foreach(_dll ${_dep_dlls})
+    file(COPY "${_dll}" DESTINATION "${CMAKE_BINARY_DIR}/bin")
+  endforeach()
+else()
+  # The QtOpcUa backend plugin uses $ORIGIN-relative RUNPATH that resolves to
+  # qtopcua-install/lib/. Symlink the open62541 libs there so dlopen finds them.
+  file(GLOB _open62541_libs "${OPEN62541_INSTALL_DIR}/lib/libopen62541*")
+  foreach(_lib ${_open62541_libs})
+    get_filename_component(_name ${_lib} NAME)
+    if(NOT EXISTS "${QTOPCUA_INSTALL_DIR}/lib/${_name}")
+      file(CREATE_LINK ${_lib} "${QTOPCUA_INSTALL_DIR}/lib/${_name}" SYMBOLIC)
+    endif()
+  endforeach()
+endif()